U.S. patent application number 12/835871 was filed with the patent office on 2011-01-20 for curable silicone compositions.
This patent application is currently assigned to WACKER CHEMIE AG. Invention is credited to Andreas Koellnberger.
Application Number | 20110015336 12/835871 |
Document ID | / |
Family ID | 42752105 |
Filed Date | 2011-01-20 |
United States Patent
Application |
20110015336 |
Kind Code |
A1 |
Koellnberger; Andreas |
January 20, 2011 |
Curable Silicone Compositions
Abstract
The present invention relates to silicone compositions which can
be crosslinked thermally by hydrosilylation, processes for
producing them and also the use of the crosslinkable
compositions.
Inventors: |
Koellnberger; Andreas;
(Marktl, DE) |
Correspondence
Address: |
BROOKS KUSHMAN P.C.
1000 TOWN CENTER, TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075
US
|
Assignee: |
WACKER CHEMIE AG
Munich
DE
|
Family ID: |
42752105 |
Appl. No.: |
12/835871 |
Filed: |
July 14, 2010 |
Current U.S.
Class: |
524/547 ;
526/126 |
Current CPC
Class: |
C09D 183/04 20130101;
C08K 5/5425 20130101; C08L 83/04 20130101; C09D 183/04 20130101;
C08G 77/12 20130101; C08K 5/14 20130101; C08L 83/00 20130101; C08L
83/00 20130101; C08K 5/05 20130101; C08L 83/04 20130101; C09K
3/1018 20130101; C08L 2205/02 20130101; C08L 2205/03 20130101; C08G
77/20 20130101 |
Class at
Publication: |
524/547 ;
526/126 |
International
Class: |
C08L 43/04 20060101
C08L043/04; C08F 4/80 20060101 C08F004/80 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 20, 2009 |
DE |
10 2009 027 847.8 |
Claims
1. An addition-crosslinking composition comprising at least one
compound bearing at least two unsaturated carbon-carbon bonds and
at least one organosilicon compound containing at least two
Si-bonded hydrogen atoms, wherein (A) is an organic compound or an
organosilicon compound containing at least two radicals having
aliphatic carbon-carbon multiple bonds, (B) is an organosilicon
compound containing at least two Si-bonded hydrogen atoms, (C) is
an organosilicon compound containing SiC-bonded radicals having
aliphatic carbon-carbon multiple bonds and Si-bonded hydrogen
atoms, (D) is a platinum catalyst, (K) is a hydroperoxide, (L) is
an acetylenic alcohol, the composition comprising at least one
compound each of (A), (B), (D), (K), and (L); at least one compound
each of (C), (D), (K), and (L); or at least one compound each of
(A), (B), (C), (D), (K), and (L).
2. The addition-crosslinking silicone composition of claim 1,
further comprising, as a component (E), at least one inhibitor or
stabilizer different from (K) and (L) in a proportion of from
0.00001% to 5% based on the total weight of the composition.
3. The addition-crosslinking silicone composition of claim 1,
further comprising at least one component (F) selected from the
group consisting of reinforcing and nonreinforcing fillers,
dispersants, solvents, bonding agents, pigments, dyes,
plasticizers, organic polymers, heat stabilizers, fungicides,
fragrances, rheological additives, corrosion inhibitors, oxidation
inhibitors, light stabilizers, flame retardants and agents for
influencing electrical properties.
4. The addition-crosslinking silicone composition of claim 2,
further comprising at least one component (F) selected from the
group consisting of reinforcing and nonreinforcing fillers,
dispersants, solvents, bonding agents, pigments, dyes,
plasticizers, organic polymers, heat stabilizers, fungicides,
fragrances, rheological additives, corrosion inhibitors, oxidation
inhibitors, light stabilizers, flame retardants and agents for
influencing electrical properties.
5. A process for producing an addition-crosslinking silicone
composition of claim 1, comprising mixing at least one compound
each of (A), (B), (D), (K) and (L), or at least one compound each
of (C), (D), (K) and (L), or at least one compound each of (A),
(B), (C), (D), (K) and (L).
6. The process of claim 5, further comprising mixing into the
addition-crosslinking silicon composition at least one further
component selected from the group consisting of (E) and (F).
7. In a process for the production of silicone moldings, silicone
coatings, silicon casts, or for impregnating, sealing, embedding,
or potting, wherein a crosslinkable organosilicon composition is
used, the improvement comprising employing, as a crosslinkable
organosilicon composition, the addition-crosslinking composition of
claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to German Patent
Application No. DE 10 2009 027 847.8 filed Jul. 20, 2009 which is
herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to silicone compositions which
can be crosslinked thermally by hydrosilylation, processes for
producing them, and to the use of the crosslinkable
compositions.
[0004] 2. Background Art
[0005] To crosslink addition-crosslinking silicone compositions by
means of the hydrosilylation reaction, a catalyst which typically
contains platinum or a metal of the platinum group is generally
used. In the catalytic reaction, aliphatically unsaturated groups
are reacted with Si-bonded hydrogen to form network structures.
[0006] In the case of two-component systems, the reactive
constituents are mixed only shortly before processing. The mixtures
contain an active platinum catalyst, as a result of which the
crosslinking reaction proceeds even at room temperature and the
time for processing (pot life) is strictly limited. This results in
disadvantages such as an additional mixing step, an increased
outlay for cleaning in the case of technical malfunctions and the
risk of platinum contamination in vessels.
[0007] There has been a long felt need for one-component
addition-crosslinking silicone rubber systems which ideally do not
cure at all at room temperature and cure very quickly at elevated
temperature.
[0008] There are various approaches to solving the problem of
premature crosslinking at room temperature. One possibility is to
encapsulate the catalyst in a thermoplastic material which melts at
elevated temperature and thereby sets the active catalyst free, as
described, for example, in EP 0 459 464 A2. However, the production
of the catalyst is relatively complicated.
[0009] A further possible method of preventing premature
crosslinking of one-component systems at room temperature is the
use of specific platinum complexes. Platinum-alkynyl complexes have
been described in U.S. Pat. No. 6,252,028 B and in U.S. Pat. No.
6,359,098 B. Pt(0)-phosphine and -phosphite complexes in
combination with tin salts are used in U.S. Pat. No. 4,256,616 A,
and WO 03/098 890 A1 describes Pt(0)-phosphite complexes which
contain both phosphite ligands and divinyldisiloxane ligands as
structural features.
[0010] A further, fundamentally different possibility is to use
inhibitors which are added to the mixture as additives in order to
extend the pot life. They are always used in a molar excess over
the catalyst component and inhibit its catalytic activity. However,
an increasing amount of inhibitor results not only in a lengthening
of the pot life but also a decrease in the reactivity of the system
at elevated temperatures and an increase in the initiation
temperature. There are numerous examples of inhibitors from various
classes of substances in the literature. U.S. Pat. No. 3,723,567 A
claims amino-functional silanes as inhibitors. Alkyldiamines in
combination with an acetylenically unsaturated alcohol are used for
inhibition in U.S. Pat. No. 5,270,422 A. EP 0 761 759 A2 claims a
combination of inhibitors; an amine together with an acetylene
alcohol as a further inhibitor is used. DE 19 757 221 A1 likewise
describes the class of phosphites for use as an inhibitor.
Phosphines are claimed in U.S. Pat. No. 4,329,275 A as additive for
inhibition. A combination of phosphites with organic peroxides is
described by EP 1 437 382 A1. Apart from adverse effects on the
crosslinking kinetics, the use of sometimes volatile inhibitors or
inhibitors which liberate volatile constituents is likewise
disadvantageous. Mixtures which display complete inhibition at room
temperature and no effect at all on the reaction rate under curing
conditions by use of an appropriate additive have hitherto been
unknown.
[0011] Although the compositions previously described provide
significantly improved pot lives and at times, a sufficient
crosslinking rate for addition-crosslinking compositions formulated
as one component, there continues to be a need for
higher-performance platinum catalysts which ensure rapid
crosslinking of the material at elevated temperature but do not
display the abovementioned disadvantages.
SUMMARY OF THE INVENTION
[0012] It was an object of the present invention to provide
addition-crosslinking compositions which do not display the
abovementioned disadvantages and allow significantly improved pot
lives combined with a good crosslinking rate.
[0013] These and other objects are achieved through the use of
addition curable organosilicon compositions which crosslink through
hydrosilylation, which contain an inhibitor system comprising a
hydroperoxide and an acetylenic alcohol.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0014] In the following, the term "organopolysiloxanes" encompasses
polymeric, oligomeric and also dimeric siloxanes.
[0015] The present patent application provides
addition-crosslinking silicone compositions of the following
compositions:
[0016] at least one compound each of (A), (B), (D), (K) and
(L),
[0017] at least one compound each of (C), (D), (K) and (L)
[0018] or
[0019] at least one compound each of (A), (B), (C), (D), (K) and
(L),
where [0020] (A) is an organic compound or an organosilicon
compound containing at least two radicals having aliphatic
carbon-carbon multiple bonds, [0021] (B) is an organosilicon
compound containing at least two Si-bonded hydrogen atoms, [0022]
(C) is an organosilicon compound containing SiC-bonded radicals
having aliphatic carbon-carbon multiple bonds and Si-bonded
hydrogen atoms, [0023] (D) is a platinum catalyst, [0024] (K) is a
hydroperoxide, and [0025] (L) is an acetylenic alcohol.
[0026] It has surprisingly been discovered that the use of a
combination of one or more acetylenic alcohols (L) with one or more
hydroperoxides (K) results in a synergistic effect so that the
start temperature increases only moderately while the pot life is
significantly improved. This effect cannot be achieved solely by
use of individual inhibitors.
[0027] The compositions of the invention can be one-component
silicone compositions and also two-component silicone compositions.
In the latter case, the two components of the compositions of the
invention can contain all constituents in any combination,
generally with the proviso that a component does not simultaneously
contain siloxanes having an aliphatic multiple bond, siloxanes
having Si-bonded hydrogen and catalyst, i.e. essentially not
simultaneously the constituents (A), (B) and (D), or the
constituents (C) and (D). However, the compositions of the
invention are preferably one-component compositions.
[0028] The compounds (A) and (B) and (C) used in the compositions
of the invention are, as is known, selected so that crosslinking is
possible. Thus, for example, compound (A) may have at least two
aliphatically unsaturated radicals and (B) may have at least three
Si-bonded hydrogen atoms, or compound (A) may have at least three
aliphatically unsaturated radicals and siloxane (B) may have at
least two Si-bonded hydrogen atoms, or else siloxane (C) which has
aliphatically unsaturated radicals and Si-bonded hydrogen atoms in
ratios of from 0.1 to 10, preferably from 0.2 to 5, is used instead
of compounds (A) and (B). Mixtures of (A) and (B) and (C) having
the abovementioned ratios of aliphatically unsaturated radicals and
Si-bonded hydrogen atoms are also possible.
[0029] The compound (A) used according to the invention can be a
silicon-free organic compound having preferably at least two
aliphatically unsaturated groups or an organosilicon compound
preferably having at least two aliphatically unsaturated groups, or
a mixture thereof.
[0030] Examples of silicon-free organic compounds (A) are
1,3,5-trivinylcyclohexane, 2,3-dimethyl-1,3-butadiene,
7-methyl-3-methylene-1,6-octadiene, 2-methyl-1,3-butadiene,
1,5-hexadiene, 1,7-octadiene,
4,7-methylene-4,7,8,9-tetrahydroindene, methylcyclopentadiene,
5-vinyl-2-norbornene, bicyclo [2.2.1]hepta-2,5-diene,
1,3-diisopropenylbenzene, polybutadiene containing vinyl groups,
1,4-divinylcyclohexane, 1,3,5-triallylbenzene,
1,3,5-trivinylbenzene, 1,2,4-trivinylcyclohexane,
1,3,5-triisopropenylbenzene, 1,4-divinylbenzene,
3-methyl-1,5-heptadiene, 3-phenyl-1,5-hexadiene,
3-vinyl-1,5-hexadiene and 4,5-dimethyl-4,5-diethyl-1,7-octadiene,
N,N'-methylenebisacrylamide, 1,1,1-tris(hydroxymethyl)propane
triacrylate, 1,1,1-tris(hydroxymethyl)propane trimethacrylate,
tripropylene glycol diacrylate, diallyl ether, diallylamine,
diallyl carbonate, N,N'-diallylurea, triallylamine,
tris(2-methylallyl)amine, 2,4,6-triallyloxy-1,3,5-triazine,
triallyl-s-triazine-2,4,6(1H,3H,5H)trione, diallyl malonate,
polyethylene glycol diacrylate, polyethylene glycol dimethacrylate,
and polypropylene glycol) methacrylate.
[0031] The silicone compositions of the invention preferably
contain, as constituent (A), at least one aliphatically unsaturated
organosilicon compound. It is possible to use all aliphatically
unsaturated organosilicon compounds which are useful in
addition-crosslinking compositions, for example silicone block
copolymers with urea segments, silicone block copolymers with amide
segments, imide segments, esteramide segments, polystyrene
segments, silarylene segments, or carborane segments, silicone
polymers containing more than one of the aforementioned segments,
and silicone graft copolymers having ether groups.
[0032] As organosilicon compounds (A) which have SiC-bonded
radicals having aliphatic carbon-carbon multiple bonds, preference
is given to using linear or branched organopolysiloxanes composed
of units of the general formula (II)
R.sub.aR.sup.4.sub.bSiO.sub.(4-a-b)/2 (II),
where [0033] the radicals R are identical or different and are
each, independently of one another, an organic or inorganic radical
which is free of aliphatic carbon-carbon multiple bonds, [0034] the
radicals R.sup.4 are identical or different and are each,
independently of one another, a monovalent, substituted or
unsubstituted, SiC-bonded hydrocarbon radical having at least one
aliphatic carbon-carbon multiple bond, [0035] a is 0, 1, 2 or 3 and
[0036] b is 0, 1 or 2, with the proviso that the sum a+b is less
than or equal to 3 and there are at least 2 radicals R.sup.4 per
molecule.
[0037] The radicals R can be monovalent or polyvalent radicals,
with the polyvalent radicals, for example bivalent, trivalent or
tetravalent radicals, which then joining a plurality of, for
instance, two, three or four, siloxy units of the formula (II) to
one another.
[0038] Further examples of R are the monovalent radicals --F, --Cl,
--Br, OR.sup.5, --CN, --SCN, --NCO and SiC-bonded, substituted or
unsubstituted hydrocarbon radicals which may be interrupted by
oxygen atoms or the group --C(O)--, and also divalent radicals
bound at both ends via Si as per formula (II). If the radical R is
an SiC-bonded, substituted hydrocarbon radical, preferred
substituents are halogen atoms, phosphorus-containing radicals,
cyano radicals, --OR.sup.5, --NR.sup.5--, --NR.sup.5.sub.2,
--NR.sup.5--C(O)--NR.sup.5.sub.2, --C(O)--NR.sup.5.sub.2,
--C(O)R.sup.5, --C(O)OR.sup.5, --SO.sub.2-Ph and --C.sub.6F.sub.5.
Here, the radicals R.sup.5 are identical or different and are each
a hydrogen atom or a monovalent hydrocarbon radical having from 1
to 20 carbon atoms and Ph is the phenyl radical.
[0039] Examples of radicals R are alkyl radicals such as the
methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl,
n-pentyl, isopentyl, neopentyl, and tert-pentyl radicals, hexyl
radicals such as the n-hexyl radical, heptyl radicals such as the
n-heptyl radical, octyl radicals such as the n-octyl radical and
isooctyl radicals such as the 2,2,4-trimethylpentyl radical, nonyl
radicals such as the n-nonyl radical, decyl radicals such as the
n-decyl radical, dodecyl radicals such as the n-dodecyl radical and
octadecyl radicals such as the n-octadecyl radical; cycloalkyl
radicals such as cyclopentyl, cyclohexyl, cycloheptyl and
methylcyclohexyl radicals; aryl radicals such as the phenyl,
naphthyl, anthryl and phenanthryl radicals; alkaryl radicals such
as o-, m-, p-tolyl radicals, xylyl radicals and ethylphenyl
radicals; and aralkyl radicals such as the benzyl radical, and the
.alpha.- and the .beta.-phenylethyl radicals.
[0040] Examples of substituted radicals R are haloalkyl radicals
such as the 3,3,3-trifluoro-n-propyl radical, the
2,2,2,2',2',2'-hexafluoroisopropyl radical, the
heptafluoroisopropyl radical, haloaryl radicals such as the o-, m-
and p-chlorophenyl radicals,
--(CH.sub.2)--N(R.sup.5)C(O)NR.sup.5.sub.2,
--(CH.sub.2).sub.n--C(O)NR.sup.5.sub.2,
--(CH.sub.2).sub.n--C(O)R.sup.5, --(CH.sub.2).sub.n--C(O)OR.sup.5,
--(CH.sub.2).sub.n--C(O)NR.sup.5.sub.2,
--(CH.sub.2)--C(O)--(CH.sub.2).sub.mC(O)CH.sub.3,
--(CH.sub.2)--O--CO--R.sup.5,
--(CH.sub.2)--NR.sup.S--(CH.sub.2).sub.m--NR.sup.5.sub.2,
--(CH.sub.2).sub.n--O--(CH.sub.2).sub.mCH(OH)CH.sub.2OH,
--(CH.sub.2).sub.n(OCH.sub.2CH.sub.2).sub.mOR.sup.5,
--(CH.sub.2).sub.n--SO.sub.2-Ph and
--(CH.sub.2).sub.n--O--C.sub.6F.sub.5, where R.sup.5 and Ph are as
defined above and n and m are identical or different integers in
the range from 0 to 10.
[0041] Examples of R are divalent radicals which are Si-bonded at
both ends as per formula (II) and are derived from the monovalent
examples given above for the radical R in that an additional bond
is formed by replacement of a hydrogen atom; examples of such
radicals are --(CH.sub.2)--, --CH(CH.sub.3)--,
--C(CH.sub.3).sub.2--, --CH(CH.sub.3)--CH.sub.2--,
--C.sub.6H.sub.4--, --CH(Ph)-CH.sub.2--, --C(CF.sub.3).sub.2--,
--(CH.sub.2).sub.n--C.sub.6H.sub.4--(CH.sub.2).sub.n--,
--(CH.sub.2).sub.n--C.sub.6H.sub.4--C.sub.6H.sub.4--(CH.sub.2).sub.n--,
--(CH.sub.2O).sub.m, (CH.sub.2CH.sub.2O).sub.m, and
--(CH.sub.2).sub.n--O.sub.x--C.sub.6H.sub.4--SO.sub.2--C.sub.6H.sub.4--O.-
sub.x--(CH.sub.2).sub.n--, where x is 0 or 1 and Ph, m and n are as
defined above.
[0042] The radical R is preferably a monovalent, SiC-bonded,
substituted or unsubstituted hydrocarbon radical which is free of
aliphatic carbon-carbon multiple bonds and has from 1 to 18 carbon
atoms, more preferably a monovalent, SiC-bonded hydrocarbon radical
which is free of aliphatic carbon-carbon multiple bonds and has
from 1 to 6 carbon atoms, and in particular, the methyl or phenyl
radical.
[0043] Radicals R.sup.4 can be any groups which are capable of an
addition reaction (hydrosilylation) with an SiH-functional
compound. If the radical R.sup.4 is an SiC-bonded, substituted
hydrocarbon radical, preferred substituents are halogen atoms,
cyano radicals and --OR.sup.5, where R.sup.5 is as defined
above.
[0044] The radicals R.sup.4 are preferably alkenyl and alkynyl
groups having from 2 to 16 carbon atoms, e.g. vinyl, allyl,
methallyl, 1-propenyl, 5-hexenyl, ethynyl, butadienyl, hexadienyl,
cyclopentenyl, cyclopentadienyl, cyclohexenyl,
vinylcyclohexylethyl, divinylcyclohexylethyl, norbornenyl,
vinylphenyl and styryl radicals, with vinyl, allyl and hexenyl
radicals being particularly preferred.
[0045] The molecular weight of the constituent (A) can vary within
wide limits, for instance in the range from 10.sup.2 to 10.sup.6
g/mol. Thus, the constituent (A) can be, for example, a relatively
low molecular weight alkenyl-functional oligosiloxane, such as
1,2-divinyltetramethyldisiloxane, but can also be a high-polymer
polydimethylsiloxane having lateral or terminal Si-bonded vinyl
groups, e.g. a polydimethylsiloxane of this type having a molecular
weight of 10.sup.5 g/mol (number average determined by means of
NMR). The structure of the molecules forming the constituent (A) is
also not fixed; in particular, the structure of a relatively high
molecular weight, i.e. oligomeric or polymeric siloxane, can be
linear, cyclic, branched or resin-like, network-like. Linear and
cyclic polysiloxanes are preferably made up of units of the
formulae R.sub.3SiO.sub.1/2, R.sup.4R.sub.2SiO.sub.2/2,
R.sup.4RSiO.sub.1/2 and R.sub.2SiO.sub.2/2, where R and R.sup.4 are
as defined above. Branched and network-like polysiloxanes
additionally contain trifunctional and/or tetrafunctional units,
with preference being given to those of the formulae RSiO.sub.3/2,
R.sup.4SiO.sub.3/2 and SiO.sub.4/2. Of course, mixtures of
different siloxanes which satisfy the criteria of constituent (A)
can also be used.
[0046] As component (A), particular preference is given to using
vinyl-functional, essentially linear polydiorganosiloxanes having a
viscosity of from 0.01 to 500,000 Pas, more preferably from 0.1 to
100,000 Pas, in each case at 25.degree. C.
[0047] As organosilicon compound (B), it is possible to use all
hydrogen-functional organosilicon compounds which are useful in
addition-crosslinking compositions. As organopolysiloxanes (B)
having Si-bonded hydrogen atoms, preference is given to using
linear, cyclic or branched organopolysiloxanes composed of units of
the general formula (III)
R.sub.cH.sub.dSiO.sub.(4-c-d)/2 (III)
where [0048] R is as defined above, [0049] c is 0, 1, 2 or 3 and
[0050] d is 0, 1 or 2, with the proviso that the sum of c+d is less
than or equal to 3 and at least two Si-bonded hydrogen atoms are
present per molecule.
[0051] The organopolysiloxane (B) preferably contains Si-bonded
hydrogen in a proportion of from 0.04 to 1.7 percent by weight,
based on the total weight of the organopolysiloxane (B). The
molecular weight of the constituent (B) can likewise vary within
wide limits, for instance in the range from 10.sup.2 to 10.sup.6
g/mol. Thus, the constituent (B) can be, for example, a relatively
low molecular weight SiH-functional oligosiloxane such as
tetramethyldisiloxane but can also be a high-polymer
polydimethylsiloxane having lateral or terminal SiH groups or a
silicone resin having SiH groups.
[0052] The structure of the molecules forming the constituent (B)
is also not fixed; in particular, the structure of a relatively
high molecular weight, i.e. oligomeric or polymeric, SiH-containing
siloxane can be linear, cyclic, branched or resin-like,
network-like. Linear and cyclic polysiloxanes (B) are preferably
made up of units of the formulae R.sub.3SiO.sub.1/2,
HR.sub.2SiO.sub.1/2, HRSiO.sub.2/2 and R.sub.2SiO.sub.2/2, where R
is as defined above. Branched and network-like polysiloxanes
additionally contain trifunctional and/or tetrafunctional units,
with preference being given to those of the formulae RSiO.sub.3/2,
HSiO.sub.3/2 and SiO.sub.4/2, where R is as defined above.
[0053] Of course, it is also possible to use mixtures of different
siloxanes which satisfy the criteria of the constituent (B).
Particular preference is given to using low molecular weight
SiH-functional compounds such as tetrakis(dimethylsiloxy)silane and
tetramethylcyclotetrasiloxane and also relatively high molecular
weight, SiH-containing siloxanes such as
poly(hydrogenmethyl)siloxane and
poly(dimethylhydrogenmethyl)siloxane having a viscosity at
25.degree. C. of from 10 to 10,000 mPas, or analogous
SiH-containing compounds in which part of the methyl groups has
been replaced by 3,3,3-trifluoropropyl or phenyl groups.
[0054] Constituent (B) is preferably present in the crosslinkable
silicone compositions of the invention in such an amount that the
molar ratio of SiH groups to aliphatically unsaturated groups from
(A) is from 0.1 to 20, more preferably from 1.0 to 5.0.
[0055] The components (A) and (B) used according to the invention
are commercial products or can be prepared by processes customary
in chemistry.
[0056] Instead of components (A) and (B), the silicone compositions
of the invention can contain organopolysiloxanes (C) which at the
same time have aliphatic carbon-carbon multiple bonds and Si-bonded
hydrogen atoms. It is also possible for the silicone compositions
of the invention to contain all three components (A), (B) and
(C).
[0057] If siloxanes (C) are used, they are preferably siloxanes
composed of units of the general formulae (IV), (V) and (VI)
R.sub.fSiO.sub.4-f/2 (IV)
R.sub.gR.sup.4SiO.sub.3-g/2 (V)
R.sub.hHSiO.sub.3-h/2 (VI)
where [0058] R and R.sup.4 are as defined above, [0059] f is 0, 1,
2 or 3, [0060] g is 0, 1 or 2 and [0061] h is 0, 1 or 2, with the
proviso that at least 2 radicals R.sup.4 and at least 2 Si-bonded
hydrogen atoms are present per molecule.
[0062] Examples of organopolysiloxanes (C) are siloxanes composed
of SiO.sub.4/2, R.sub.3SiO.sub.1/2, R.sub.2R.sup.4SiO.sub.1/2 and
R.sub.2HSiO.sub.1/2 units, known as MQ resins, with these resins
additionally being able to contain RSiO.sub.3/2 and R.sub.2SiO
units, and also linear organopolysiloxanes consisting essentially
of R.sub.2R.sup.4SiO.sub.1/2, R.sub.2SiO and RHSiO units, where R
and R.sup.4 are as defined above. The organopolysiloxanes (C)
preferably have an average viscosity of from 0.01 to 500,000 Pas,
more preferably from 0.1 to 100,000 Pas, in each case at 25.degree.
C. Organopolysiloxanes (C) can be prepared by methods customary in
chemistry.
[0063] As catalysts (D) which promote the addition of Si-bonded
hydrogen onto aliphatic multiple bonds, all catalysts (D) which are
useful for promoting the addition of Si-bonded hydrogen onto
aliphatic multiple bonds can be used in the process of the
invention. The catalysts are preferably a metal from the group of
the platinum metals or a compound or a complex from the group of
the platinum metals. Examples of such catalysts (D) are metallic
and finely divided platinum which may be present on supports such
as silicon dioxide, aluminium oxide or activated carbon, compounds
or complexes of platinum such as platinum halides, e.g. PtCl.sub.4,
H.sub.2PtCl.sub.6.6H.sub.2O, Na.sub.2PtCl.sub.4.4H.sub.2O,
platinum-olefin complexes, platinum-phosphite complexes,
platinum-alcohol complexes, platinum-alkoxide complexes,
platinum-ether complexes, platinum-aldehyde complexes,
platinum-ketone complexes including reaction products of
H.sub.2PtCl.sub.6.6H.sub.2O and cyclohexanone,
platinum-vinylsiloxane complexes such as
platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes with
or without a content of detectable inorganically bound halogen,
bis(gamma-picoline)platinum dichloride,
trimethylenedipyridineplatinum dichloride,
dicyclopentadieneplatinum dichloride, dimethylsulfoxide
ethyleneplatinum(II) dichloride, cyclooctadieneplatinum dichloride,
norbornadieneplatinum dichloride, gamma-picolineplatinum
dichloride, cyclopentadieneplatinum dichloride, and also reaction
products of platinum tetrachloride with olefin and primary amine or
secondary amine or primary and secondary amine, for example the
reaction product of platinum tetrachloride dissolved in 1-octene
with sec-butylamine, or ammonium-platinum complexes.
[0064] In the process of the invention, the catalyst (D) is
preferably used in amounts of from 0.5 to 100 ppm by weight (parts
by weight per million parts by weight), more preferably in amounts
of from 5 to 50 ppm by weight, in each case calculated as elemental
platinum and based on the total weight of the silicone
composition.
[0065] As component (K), it is possible to use all hydroperoxides
known in the prior art, for example cumene hydroperoxide,
tert-butyl hydroperoxide, pinane hydroperoxide, 5-phenyl-4-pentenyl
hydroperoxide, 2-butanone peroxide
(1-[(1-hydroperoxy-1-methylpropyl)peroxy]-1-methylpropyl
hydroperoxide), etc. Preference is given to compounds which contain
both at least one hydroperoxy group and at least one peroxy group,
e.g. 2-butanone peroxide.
[0066] As component (L), it is possible to use any acetylenic
alcohol, for example those known in the art. Suitable examples are
1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol and
3,5-dimethyl-1-hexyn-3-ol or 3-methyl-1-dodecyn-3-ol. Preference is
given to using 1-ethynylcyclohexanol as component (L).
[0067] Apart from the abovementioned components (A), (B), (C), (D),
(K) and (L), further components (E) or (F) can be additionally
present in the silicone compositions of the invention.
[0068] Components (E) such as inhibitors and stabilizers which are
different from (K) and (L) serve to set the processing time, start
temperature and crosslinking rate of the silicone compositions of
the invention in a targeted manner. These inhibitors and
stabilizers are very well known in the field of
addition-crosslinking compositions. Examples of customary
inhibitors are polymethylvinylcyclosiloxanes such as
1,3,5,7-tetravinyltetramethyl-tetracyclosiloxane, low molecular
weight silicone oils having methylvinyl-SiO.sub.1/2 groups and/or
R.sub.2vinylSiO.sub.1/2 end groups, e.g.
divinyltetramethyldisiloxane, tetravinyldimethyldisiloxane,
trialkyl cyanurates, alkyl maleates such as diallyl maleate,
dimethyl maleate and diethyl maleate, alkyl fumarates such as
diallyl fumarate and diethyl fumarate, organic peroxides, organic
sulfoxides, organic amines, diamines and amides, phosphanes and
phosphites, nitriles, triazoles, diaziridines and oximes. The
action of these inhibitor additives (E) depends on their chemical
structure, so that the concentration has to be determined
individually Inhibitors and inhibitor mixtures are preferably added
in a proportion of from 0.00001% to 5%, based on the total weight
of the mixture, more preferably from 0.00005 to 2% and most
preferably from 0.0001 to 1%. The compositions may be free of the
optional additional stabilizers and inhibitors.
[0069] Components (F) are all further additives which are useful
for producing addition-crosslinkable compositions. The silicone
composition of the invention can, if desired, contain the component
(F) as further additives in a proportion of up to 70% by weight,
preferably from 0.0001 to 40% by weight. These additives can be,
for example, inactive fillers, resin-like polyorganosiloxanes which
are different from the siloxanes (A), (B) and (C), reinforcing and
nonreinforcing fillers, fungicides, fragrances, rheological
additives, corrosion inhibitors, oxidation inhibitors, light
stabilizers, flame retardants and agents for influencing the
electrical properties, dispersants, solvents, bonding agents,
pigments, dyes, plasticizers, organic polymers, heat stabilizers,
etc. These include additives such as quartz flour, diatomaceous
earth, clays, chalk, lithopone, carbon blacks, graphite, metal
oxides, metal carbonates, sulfates, metal salts of carboxylic
acids, metal dusts, metal hydroxides, fibers such as glass fibers,
polymer fibers, polymer powders, metal dusts, dyes, pigments,
etc.
[0070] Examples of reinforcing fillers which can be used as
component (F) in the silicone compositions of the invention are
pyrogenic or precipitated silicas having BET surface areas of at
least 50 m.sup.2/g and also carbon blacks and activated carbons
such as furnace black and acetylene black, with preference being
given to pyrogenic and precipitated silicas having BET surface
areas of at least 50 m.sup.2/g. The silica fillers mentioned can
have hydrophilic character or have been hydrophobicized by known
methods. When mixing in hydrophilic fillers, the addition of a
hydrophobicizing agent is necessary. The content of actively
reinforcing filler (F) in the crosslinkable composition of the
invention, for example, may be in the range from 0 to 70% by
weight, preferably from 0 to 50% by weight.
[0071] The silicone compositions of the invention can, if
necessary, be dissolved, dispersed in suspension or emulsified in
liquids. The compositions of the invention can, especially
depending on the viscosity of the constituents and the filler
content, have a low viscosity and be pourable, have a paste-like
consistency or be pulverulent or else be pliable, high-viscosity
compositions, as known, for example, in the case of compositions
frequently denoted among those skilled in the art as RTV-1, RTV-2,
LSR and HTV. In particular, the compositions of the invention can,
if they have a high viscosity, be converted into the form of a
granular material. Here, the individual granule can comprise all
components or the components used according to the invention are
separately incorporated into different granules. As regards the
elastomeric properties of the crosslinked silicone compositions of
the invention, the properties encompass the entire spectrum ranging
from extremely soft silicone gels, through rubber-like materials to
highly crosslinked silicones having glass-like behavior.
[0072] The silicone compositions of the invention can be produced
by known methods, for example by uniform mixing of the individual
components. Any order is possible, but preference is given to
uniformly mixing the platinum catalyst (D) with a mixture of (A),
(B) and if appropriate (E) and (F). The platinum catalyst (D) and
if appropriate (C) used according to the invention can be
incorporated as solid or as solution dissolved in a suitable
solvent or as masterbatch, viz. mixed uniformly with a small amount
of (A), or with (A) together with (E). The components (A), (B),
(C), (D), (E), (F), (K) and (L) can, in each case, be a single type
of such a component or else a mixture of at least two different
types of such a component.
[0073] The silicone compositions of the invention which can be
crosslinked by addition of Si-bonded hydrogen onto aliphatic
multiple bonds can be crosslinked under the same conditions as the
previously known compositions which can be crosslinked by means of
a hydrosilylation reaction. Preference is given to employing
temperatures of from 100 to 220.degree. C., more preferably from
130 to 190.degree. C., and at a pressure of from 900 to 1100 hPa.
However, it is also possible to employ higher or lower temperatures
and pressures.
[0074] The present invention further provides moldings produced by
crosslinking the compositions of the invention.
[0075] The silicone compositions of the invention and also the
crosslinked products produced therefrom according to the invention
can be used for all purposes for which organopolysiloxane
compositions which can be crosslinked to give elastomers or such
elastomers are useful. These encompass, for example, silicone
coating or impregnation of any substrates, the production of
moldings, for example by injection molding processes, vacuum
extrusion processes, extrusion processes, casting and compression
molding and taking casts, and use as sealing compositions,
embedding compositions and potting compositions etc.
[0076] The crosslinkable silicone compositions of the invention
have the advantage that they can be produced in a simple process
using readily available starting materials and thus economically.
The crosslinkable compositions of the invention have the further
advantage that they have a very good storage stability as
one-component formulations at 25.degree. C. and ambient pressure
and crosslink quickly only at elevated temperature. The two
components (K) and (L) surprisingly display a synergistic effect in
respect of the storage stability. The silicone compositions of the
invention have the advantage that in the case of two-component
formulations they give, after mixing the two components, a
crosslinkable silicone compositions whose processability is
maintained over a long period of time at 25.degree. C. and ambient
pressure, i.e. compositions which display extremely long pot lives
and crosslink rapidly only at elevated temperature.
[0077] Furthermore, the compositions of the invention have the
advantage that the crosslinked silicone rubbers obtained therefrom
have excellent transparency, and that the hydrosilylation reaction
does not become slower with duration of the reaction.
Examples
[0078] In the examples described below, all parts and percentages
are, unless indicated otherwise, by weight. Unless indicated
otherwise, the examples below are carried out at the pressure of
the surrounding atmosphere, i.e. at about 1000 hPa, and at room
temperature, i.e. at about 20.degree. C., or at a temperature which
is established when the reactants are combined at room temperature
without additional heating or cooling. Any possible mixture of the
above-described components (A), (B), (C) and (D) including fillers
and additives can be used as base mixture for carrying out the
examples since the base mixture has no influence on the values of
the "start temperature" and "pot life." The start temperature
reflects the point of commencement of crosslinking at 4% of the
final value, with the measurement itself being carried out using a
temperature range from 80.degree. C. to 200.degree. C. and a rate
of increase of 10 K/min. At the end of the pot life, the material
is no longer processable and replasticization is no longer
possible.
[0079] Table 1 shows the synergistic action of the combination of
one or more acetylenic alcohols (L) with one or more hydroperoxides
(K). Additives, Si--H crosslinkers and catalysts can be mixed in
any desired order, with the addition of the catalyst preferably
occurring after addition of the additives.
[0080] A crosslinkable base mixture is produced from the
above-mentioned constituents vinyl polymer, Si--H crosslinker,
fillers, with the composition of the mixture having no or only
slight influence on the relevant parameters pot life and start
temperature. All abovementioned mixing ratios are permissible for
production of this base mixture. In the present examples, the
Karstedt catalyst
(platinum-1,3-divinyl-1,1,3,3-tetra-methyldisiloxane complexes) is
used, but it is also possible to use all other known catalysts of
the platinum group. The indicated amounts of the hydroperoxides are
in each case based on the sum of the solutions or mixtures used and
the following abbreviations are employed:
2-butanone peroxide: 50-60% strength in diacetone alcohol (BPO)
tert-butyl hydroperoxide: 5-6 M in decane (tBuHPO) cumene
hydroperoxide: technical-grade 80% strength (CHPO) Ex. No. (Example
number) Cat. (catalyst) RT (room temperature) n.c.o. (not carried
out) ECH: 1-ethynylcyclohexanol
TABLE-US-00001 TABLE 1 Cat Hydro- Start Ex. in Inhibitor peroxide
temperature Pot life in days No. ppm in ppm in % in .degree. C. at
50.degree. C. at RT 1* 5 500 (ECH) 0 108 3 41 2 5 500 (ECH) 0.01
(BPO) 119 3 75 3 5 500 (ECH) 0.05 (BPO) 140 11 250 4 5 500 (ECH)
0.1 (BPO) 153 25 >360 5* 5 0 (ECH) 0.05 (BPO) 86 0.3 5 6* 5 0
(ECH) 0.1 (BPO) 92 2 47 7 5 50 (ECH) 0.2 (BPO) 107 2 80 8 5 50
(ECH) 0.3 (BPO) 115 4 101 9 5 50 (ECH) 0.4 (BPO) 136 10 164 10* 0 1
(BPO) not n.c.o. n.c.o. 0 crosslinked 11 5 100 (ECH) 0.2 (BPO) 114
2 73 12 5 150 (ECH) 0.2 (BPO) 126 4 101 13 5 200 (ECH) 0.2 (BPO)
133 7 136 14 5 500 (ECH) 0.01 122 4 70 (tBuHPO) 15 5 500 (ECH) 0.05
145 8 200 (tBuHPO) 16 5 500 (ECH) 0.1 (tBuHPO) 150 15 >360 17* 0
0 1 (tBuHPO) not n.c.o. n.c.o. crosslinked 18 5 500 (ECH) 0.01
(CHPO) 123 3 65 19 5 500 (ECH) 0.05 (CHPO) 138 9 230 20 5 500 (ECH)
0.1 (CHPO) 144 18 300 21* 0 0 1 (CHPO) not n.c.o. n.c.o.
crosslinked 22* 5 1000 (ECH) -- 135 4 120 23* 5 2000 (ECH) -- 150 5
250 *not according to the invention
[0081] In the examples of Table 1, the base mixture is mixed with
the inhibitors (acetylenic alcohol and hydroperoxide) before the
platinum catalyst is added.
[0082] Table 1 shows the composition and results. Examples 10, 17
and 21 clearly show that the hydroperoxide added serves as
inhibitor for the platinum-catalyzed hydrosilylation and that
peroxide-induced crosslinking consequently takes place since
compositions without platinum catalyst do not crosslink. Examples 5
and 6 show that in the case of the sole use of hydroperoxide as
inhibitor, the hydrosilylation is not sufficiently inhibited
without addition of acetylenic alcohol. However, if a combination
of acetylenic alcohol and hydroperoxide is added to the mixtures
(Examples 2, 3, 4, 14, 15, 16, 18, 19, 20), it is possible, in
particular, to achieve an overproportionate increase in the
room-temperature pot life. Surprisingly, a synergistic effect is
observed as a result of the combination of the two inhibitors. The
start temperature of these mixtures increases only moderately in
comparison with the pot life (particularly the room-temperature pot
life). A further advantage arising from the combination of the two
classes of compounds is that a significantly smaller total amount
of inhibitors has to be mixed in in order to obtain the same pot
life. Particularly when the materials are used as insulating
materials, this is a significant advantage (a smaller amount of
dissociation products and by-products is formed).
[0083] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *